Image sensors and methods of fabricating the same

ABSTRACT

An image sensor includes a photoelectric conversion element in a substrate, a first storage region spaced apart from the photoelectric conversion element in the substrate, a gate on the first storage region, a light shielding layer covering the gate, a dielectric layer disposed between the gate and the light shielding layer and extending onto a top surface of the substrate, an interlayer insulating structure covering the light shielding layer, and a micro-lens overlapping with the photoelectric conversion element on the interlayer insulating structure. The light shielding layer includes a first portion covering a sidewall of the gate, and a second portion on a top surface of the gate. The first portion has a first thickness corresponding to a vertical height from a bottom surface of the first portion to a top surface of the first portion, and the first thickness is greater than a second thickness of the second portion.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 to Korean Patent Application No. 10-2014-0098251, filed onJul. 31, 2014, in the Korean Intellectual Property Office, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

The inventive concepts relate to image sensors and methods offabricating the same. More particularly, the inventive concepts relateto image sensors including a shutter gate and methods of fabricating thesame.

An image sensor is a semiconductor device that converts an optical imageinto an electrical signal. Image sensors may be categorized as any oneof charge coupled device (CCD) image sensors and complementarymetal-oxide-semiconductor (CMOS) image sensors. CIS is short for theCMOS image sensor. The CIS may include a plurality of pixelstwo-dimensionally arranged. Each of the pixels may include a photodiodethat converts incident light into an electrical signal.

As applications with high dynamic range are being demanded, additionalgates may be used to increase functional operations (e.g., electronicshuttering, etc.) of the pixels.

SUMMARY

Embodiments of the inventive concepts may provide image sensors capableof improving shuttering efficiency.

Embodiments of the inventive concepts may also provide methods offabricating an image sensor with improved sensitivity.

In one aspect, an image sensor may include: a substrate; a photoelectricconversion element disposed in the substrate; a first storage regiondisposed in the substrate and spaced apart from the photoelectricconversion element; a gate disposed on the first storage region; a lightshielding layer covering the gate; a dielectric layer disposed betweenthe gate and the light shielding layer and extending onto a top surfaceof the substrate; an interlayer insulating structure covering the lightshielding layer on the substrate; and a micro-lens disposed on theinterlayer insulating structure and overlapping with the photoelectricconversion element. The light shielding layer may include: a firstportion covering a sidewall of the gate; and a second portion disposedon a top surface of the gate. The first portion of the light shieldinglayer may have a first thickness corresponding to a vertical height froma bottom surface of the first portion to a top surface of the firstportion. The first thickness of the first portion of the light shieldinglayer may be greater than a second thickness of the second portion ofthe light shielding layer.

In another aspect, a method of fabricating an image sensor may include:forming a gate on a substrate including a pixel region and a peripheralcircuit region; forming a dielectric layer covering a surface of thegate on the substrate; removing the dielectric layer of the peripheralcircuit region to expose a dopant region formed in the substrate of theperipheral circuit region; forming a silicide layer on the dopantregion; forming an interlayer insulating layer having an openingoverlapping with the gate covered with the dielectric layer; performingan etch-back process to recess the dielectric layer exposed by theopening; and forming a light shielding layer by filling the opening witha metal material.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concepts will become more apparent in view of the attacheddrawings and accompanying detailed description.

FIG. 1 is a circuit diagram illustrating a unit pixel of an active pixelsensor (APS) array of an image sensor according to example embodimentsof the inventive concepts;

FIG. 2 is a plan view illustrating an image sensor according to someembodiments of the inventive concepts;

FIG. 3A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a first embodiment ofthe inventive concepts;

FIG. 3B is an enlarged view of a portion ‘A’ of FIG. 3A;

FIG. 4A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a second embodiment ofthe inventive concepts;

FIG. 4B is an enlarged view of a portion ‘B’ of FIG. 4A;

FIG. 5A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a third embodiment ofthe inventive concepts;

FIG. 5B is an enlarged view of a portion ‘C’ of FIG. 5A;

FIG. 6A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a fourth embodiment ofthe inventive concepts;

FIG. 6B is an enlarged view of a portion ‘D’ of FIG. 6A;

FIG. 7 is a plan view illustrating an image sensor according to a fifthembodiment of the inventive concepts;

FIG. 8 is a cross-sectional view taken along lines III-III′ and VI-VI′of FIG. 7 to illustrate the image sensor according to the fifthembodiment of the inventive concepts;

FIGS. 9A to 9I are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate a method of fabricating the image sensoraccording to the first embodiment of the inventive concepts;

FIGS. 10A to 10G are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate a method of fabricating the image sensoraccording to the second embodiment of the inventive concepts;

FIGS. 11A to 11F are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate a method of fabricating the image sensoraccording to the third embodiment of the inventive concepts;

FIGS. 12A to 12E are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate a method of fabricating the image sensoraccording to the fourth embodiment of the inventive concepts;

FIGS. 13 to 17 illustrate examples of multimedia devices implementedwith image sensors according to embodiments of the inventive concepts;and

FIG. 18 is a schematic block diagram illustrating an image processingsystem including an image sensor according to embodiments of theinventive concepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concepts will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the inventive concepts are shown. The advantages and features of theinventive concepts and methods of achieving them will be apparent fromthe following exemplary embodiments that will be described in moredetail with reference to the accompanying drawings. It should be noted,however, that the inventive concepts are not limited to the followingexemplary embodiments, and may be implemented in various forms.Accordingly, the exemplary embodiments are provided only to disclose theinventive concepts and let those skilled in the art know the category ofthe inventive concepts. In the drawings, embodiments of the inventiveconcepts are not limited to the specific examples provided herein andare exaggerated for clarity.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to limit the invention. As usedherein, the singular terms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. It will beunderstood that when an element is referred to as being “connected” or“coupled” to another element, it may be directly connected or coupled tothe other element or intervening elements may be present.

Similarly, it will be understood that when an element such as a layer,region or substrate is referred to as being “on” another element, it canbe directly on the other element or intervening elements may be present.In contrast, the term “directly” means that there are no interveningelements. It will be further understood that the terms “comprises”,“comprising,”, “includes” and/or “including”, when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Additionally, the embodiment in the detailed description will bedescribed with sectional views as ideal exemplary views of the inventiveconcepts. Accordingly, shapes of the exemplary views may be modifiedaccording to manufacturing techniques and/or allowable errors.Therefore, the embodiments of the inventive concepts are not limited tothe specific shape illustrated in the exemplary views, but may includeother shapes that may be created according to manufacturing processes.Areas exemplified in the drawings have general properties, and are usedto illustrate specific shapes of elements. Thus, this should not beconstrued as limited to the scope of the inventive concepts.

It will be also understood that although the terms first, second, thirdetc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms are only used todistinguish one element from another element. Thus, a first element insome embodiments could be termed a second element in other embodimentswithout departing from the teachings of the present invention. Exemplaryembodiments of aspects of the present inventive concepts explained andillustrated herein include their complementary counterparts. The samereference numerals or the same reference designators denote the sameelements throughout the specification.

Moreover, exemplary embodiments are described herein with reference tocross-sectional illustrations and/or plane illustrations that areidealized exemplary illustrations. Accordingly, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, exemplaryembodiments should not be construed as limited to the shapes of regionsillustrated herein but are to include deviations in shapes that result,for example, from manufacturing. For example, an etching regionillustrated as a rectangle will, typically, have rounded or curvedfeatures. Thus, the regions illustrated in the figures are schematic innature and their shapes are not intended to illustrate the actual shapeof a region of a device and are not intended to limit the scope ofexample embodiments.

As appreciated by the present inventive entity, devices and methods offorming devices according to various embodiments described herein may beembodied in microelectronic devices such as integrated circuits, whereina plurality of devices according to various embodiments described hereinare integrated in the same microelectronic device. Accordingly, thecross-sectional view(s) illustrated herein may be replicated in twodifferent directions, which need not be orthogonal, in themicroelectronic device. Thus, a plan view of the microelectronic devicethat embodies devices according to various embodiments described hereinmay include a plurality of the devices in an array and/or in atwo-dimensional pattern that is based on the functionality of themicroelectronic device.

The devices according to various embodiments described herein may beinterspersed among other devices depending on the functionality of themicroelectronic device. Moreover, microelectronic devices according tovarious embodiments described herein may be replicated in a thirddirection that may be orthogonal to the two different directions, toprovide three-dimensional integrated circuits.

Accordingly, the cross-sectional view(s) illustrated herein providesupport for a plurality of devices according to various embodimentsdescribed herein that extend along two different directions in a planview and/or in three different directions in a perspective view. Forexample, when a single active region is illustrated in a cross-sectionalview of a device/structure, the device/structure may include a pluralityof active regions and transistor structures (or memory cell structures,gate structures, etc., as appropriate to the case) thereon, as would beillustrated by a plan view of the device/structure.

FIG. 1 is a circuit diagram illustrating a unit pixel of an active pixelsensor (APS) array of an image sensor according to example embodimentsof the inventive concepts.

Referring to FIG. 1, a unit pixel P including five NMOS transistors mayinclude a photoelectric conversion element 110 receiving light togenerate photo-charges, and reading elements reading an optical signal(e.g., light) incident on the photoelectric conversion element 110. Thereading elements may include a reset element 160, an amplificationelement 170, and a selection element 180.

The photoelectric conversion element 110 may convert the incident lightinto charges and may accumulate the generated charges. The photoelectricconversion element 110 may include a photo diode, a photo transistor, aphoto gate, a pinned photo diode (PPD), or any combination thereof.

The photoelectric conversion element 110 is connected to a shutterelement 120(SG). The shutter element 120 may transfer the chargesaccumulated in the photoelectric conversion element 110 into a firstdetection element 130. The shutter element 120 is connected to atransfer element 150 that transfers the charges of the first detectionelement 130 into a second detection element 140.

The first detection element 130 may be used as a charge storage regionand may receive the charges accumulated in the photoelectric conversionelement 110. A charge storage capacity of the first detection element130 may be greater than that of the photoelectric conversion element110. The charges generated and accumulated in the photoelectricconversion element 110 may be transferred into the first detectionelement 130 at once.

The charges accumulated in the first detection element 130 may betransferred into the second detection element 140 through the transferelement 150 (TG). The second detection element 140 may be a floatingdiffusion region (FD). The second detection element 140 may storecharges cumulatively. A charge storage capacity of the second detectionelement 140 may be greater than that of the first detection element 130.The charges stored in the first detection element 130 may be transferredto the second detection element 140 at once. Since the charges generatedin the photoelectric conversion element 110 are transferred to thesecond detection element 140 through the first detection element 130 atonce, it is possible to solve an image distortion problem that may becaused by the transfer delay of charges when the charges aresequentially transferred. The second detection element 140 may beelectrically connected to the amplification element 170 to control theamplification element 170.

The reset element 160 may reset the second detection element 140 byperiods. A source of the reset element 160 may be connected to thesecond detection element 140, and a drain of the reset element 160 maybe connected to a power voltage VDD. The reset element 160 may be drivenby a bias provided through a reset signal line RX(i). If the resetelement 160 is turned-on by the bias provided through the reset signalline RX(i), the power voltage VDD connected to the drain of the resetelement 160 may be transmitted to the second detection element 140. As aresult, the second detection element 140 may be reset when the resetelement 160 is turned-on.

The amplification element 170 may be combined with a constant currentsource (not shown) located outside the unit pixel P to act as a sourcefollower buffer amplifier. The amplification element 170 may amplify avariation of an electrical potential of the second detection element 140to output the amplified potential variation to an output line.

Even though not shown in the drawings, an active contact (not shown) maybe disposed between the reset element 160 and the amplification element170. The active contact may apply a voltage to the unit pixel P.

The selection element 180 may select a unit cell to be sensed. In someembodiments, signals of all the pixels of one row may be sensed at thesame time. The selection element 180 may be driven by a bias providedthrough a row selection line SEL(i). If the selection element 180 isturned-on, the power voltage VDD connected to a drain of theamplification element 170 may be transmitted to a drain of the selectionelement 180.

Driving signal lines TX(i), TX(ii), RX(i), and SEL(i) of the shutterelement 120, the transfer element 150, the reset element 160, and theselection element 180 may extend in a row direction (e.g., a horizontaldirection) to drive the unit pixels included in the same row at the sametime.

FIG. 2 is a plan view illustrating an image sensor according to someembodiments of the inventive concepts. FIG. 3A is a cross-sectional viewtaken along lines I-I′ and II-II′ of FIG. 2 to illustrate an imagesensor according to a first embodiment of the inventive concepts. FIG.3B is an enlarged view of a portion ‘A’ of FIG. 3A.

Referring to FIGS. 2 and 3A, a semiconductor substrate 10 may include apixel region PR1 and a peripheral circuit region PR2. For example, thesemiconductor substrate 10 may be a P-type semiconductor substrate. Adevice isolation layer 13 may be disposed in the semiconductor substrate10. The device isolation layer 13 disposed in the pixel region PR1 maydefine first active regions 11 for unit pixels P. The first activeregions 11 may correspond to portions of the semiconductor substrate 10that are surrounded by the device isolation layer 13.

A photoelectric conversion element PD may be disposed in thesemiconductor substrate 10 (e.g., each of the first active regions 11)of the pixel region PR1. In some embodiments, the photoelectricconversion element PD may be a photo diode. The photoelectric conversionelement PD may include a first dopant region 15 a and a second dopantregion 15 b. The first dopant region 15 a may be formed deep from a topsurface of the semiconductor substrate 10. The second dopant region 15 bmay be formed shallow from the top surface of the semiconductorsubstrate 10. The first and second dopant regions 15 a and 15 b may haveconductivity types different from each other. For example, the firstdopant region 15 a may be doped with N-type dopants, and the seconddopant region 15 b may be doped with P-type dopants.

A charge storage region 14 may be disposed in the semiconductorsubstrate 10 (e.g., each of the first active regions 11) of the pixelregion PR1. The charge storage region 14 may be spaced part from thephotoelectric conversion element PD. The charge storage region 14 may beformed close to the top surface of the semiconductor substrate 10. Thecharge storage region 14 may be doped with N-type dopants. A well region16 may be disposed under the charge storage region 14. The well region16 may be doped with P-type dopants. A separation region 18 may bedisposed between the photoelectric conversion element PD and the chargestorage region 14. The separation region 18 may be doped with P-typedopants.

A floating diffusion region 17 may be disposed in the semiconductorsubstrate 10 (e.g., each of the first active regions 11) of the pixelregion PR1. The floating diffusion region 17 may be spaced apart fromthe charge storage region 14. The floating diffusion region 17 may bedoped with, for example, N-type dopants. The floating diffusion region17 may consist of one doped region, and an area of the floatingdiffusion region 17 may be smaller than that of the photoelectricconversion element PD.

A shutter gate SG may be disposed on the substrate 10 (e.g., each of thefirst active regions 11) of the pixel region PR1. The shutter gate SGmay be disposed on the charge storage region 14 and may be adjacent thesecond dopant region 15 b. The shutter gate SG may include a shuttergate insulating layer 21 a and a shutter gate electrode 21 b.

A transfer gate TG may be disposed on the semiconductor substrate 10(e.g., each of the first active regions 11) of the pixel region PR1. Thetransfer gate TG may be laterally spaced apart from the shutter gate SG.The transfer gate TG may be adjacent the floating diffusion region 17and may be disposed on the semiconductor substrate 10 between the chargestorage region 14 and the floating diffusion region 17. The transfergate TG may include a transfer gate insulating layer 23 a and a transfergate electrode 23 b.

Third dopant regions 19 may be disposed in the semiconductor substrate10 of the peripheral circuit region PR2. The third dopant regions 19 maybe disposed in a second active region 12 that is defined by the deviceisolation layer 13 of the peripheral circuit region PR2. The thirddopant regions 19 may be source/drain regions or a well region.

A peripheral circuit gate PG may be disposed on the semiconductorsubstrate 10 of the peripheral circuit region PR2. In some embodiments,the peripheral circuit gate PG may be disposed on the second activeregion 12 between the third dopant regions 19. The peripheral circuitgate PG may include a peripheral circuit gate insulating layer 25 a anda peripheral circuit gate electrode 25 b.

A silicide layer 35 a may be formed on each of a surface of theperipheral circuit gate electrode 25 b, the floating diffusion region17, and the third dopant regions 19. The silicide layer 35 a may be usedas an ohmic layer for reducing an electrical resistance between thesemiconductor substrate 10 formed of silicon and via-contacts 52 formedof a metal material.

A dielectric layer 31 may be formed on the semiconductor substrate 10 ofthe pixel region PR1. The dielectric layer 31 may cover the top surfaceof the semiconductor substrate 10, a top surface and a sidewall of theshutter gate SG, and a top surface and a sidewall of the transfer gateTG. The dielectric layer 31 may expose a portion of the floatingdiffusion region 17. A light shielding layer 45 may be disposed on thedielectric layer 31 to cover the shutter gate SG. In more detail, thelight shielding layer 45 may cover the top surface and the sidewall ofthe shutter gate SG. The light shielding layer 45 may include a firstportion covering sidewalls of the shutter gate SG and a second portiondisposed on the top surface of the shutter gate SG. A top surface of thedielectric layer 31, which is in contact with a bottom surface of thefirst portion of the light shielding layer 45, may be recessed. Thebottom surface of the first portion of the light shielding layer 45 maybe lower than a top surface of the dielectric layer 31 covering the topsurface of the semiconductor substrate 10 disposed at a side of thelight shielding layer 45. Thus, as illustrated in FIG. 3B, a firstthickness T1 of the dielectric layer 31 disposed on the top surface ofthe semiconductor substrate 10 not covered by the light shielding layer45 may be greater than a second thickness T2 of the dielectric layer 31disposed under the bottom surface of the first portion of the lightshielding layer 45.

A first thickness t1 of the first portion of the light shielding layer45 may be greater than a second thickness t2 of the second portion ofthe light shielding layer 45. In more detail, the first thickness t1 ofthe first portion of the light shielding layer 45 corresponds to avertical height from the top surface of the recessed dielectric layer 31to a top surface of the first portion of the light shielding layer 45.The second thickness t2 of the second portion of the light shieldinglayer 45 corresponds to a vertical height from the top surface of thedielectric layer 31 formed on the top surface of the shutter gateelectrode 21 b to a top surface of the second portion of the lightshielding layer 45. The dielectric layer 31 may include a siliconnitride (SiN) layer. The light shielding layer 45 may include a tungstenlayer or an aluminum layer. The top surface of the first portion havingthe first thickness t1 of the light shielding layer 45 may be coplanarwith the top surface of the second portion having the second thicknesst2 of the light shielding layer 45. In other words, an entire topsurface of the light shielding layer 45 may be flat.

While light is incident on the photoelectric conversion element PD, thelight shielding layer 45 shields the charge storage region 14 from thelight. If light is incident on the charge storage region 14, signalcharges stored in the charge storage region 13 may be changed which maydistort an image. The shutter gate SG may also shield the light, so thelight provided toward the semiconductor substrate 10 disposed under theshutter gate SG may be shielded by the shutter gate SG and the lightshielding layer 45. On the other hand, the light provided toward thesemiconductor substrate 10 disposed at a side of the shutter gate SG maybe shielded by the light shielding layer 45. Thus, a light shieldingeffect of the semiconductor substrate 10 disposed at a side of theshutter gate TG may be weaker than that of the semiconductor substrate10 disposed under the shutter gate TG.

According to some embodiments of the inventive concepts, the firstthickness t1 of the first portion of the light shielding layer 45 isgreater than the second thickness t2 of the second portion of the lightshielding layer 45, so the light shielding layer 45 may effectivelyshield the light provided toward the semiconductor substrate 10 underthe first portion of the light shielding layer 45. Light reflected bythe light shielding layer 45 may be provided to the photoelectricconversion element PD. As a result, an accurate image may be obtainedwithout the distortion of an image.

As described above, the second thickness T2 of the dielectric layer 31may be smaller than the first thickness T1 of the dielectric layer 31,and thus, it is possible to reduce or minimize scattered light that maybe provided between the top surface of the semiconductor substrate 10and the bottom surface of the first portion of the light shielding layer45. In other words, it is possible to reduce or minimize the scatteredlight provided to the charge storage region 14.

Referring again to FIG. 3A, a protection dielectric layer 22 may bedisposed on the semiconductor substrate 10 of the peripheral circuitregion PR1. The protection dielectric layer 22 may cover the peripheralcircuit gate PG, the silicide layer 35 a on the peripheral circuit gateelectrode 25 b, and the silicide layers 35 a on the third dopant regions19. In addition, the protection dielectric layer 22 may extend into thepixel region PR1 so as to cover the silicide layer 35 a disposed on thefloating diffusion region 17.

An interlayer insulating structure 70 may be disposed on thesemiconductor substrate 10. The interlayer insulating structure 70 mayinclude a first interlayer insulating layer 40, a second interlayerinsulating layer 50, and a third interlayer insulating layer 60. Thefirst interlayer insulating layer 40 may cover the shutter gate SG, thetransfer gate TG, and the peripheral circuit gate PG on thesemiconductor substrate 10. The first interlayer insulating layer 40 mayexpose the top surface of the light shielding layer 45. The secondinterlayer insulating layer 50 may be disposed on the first interlayerinsulating layer 40. The via-contacts 52 may penetrate the second andfirst interlayer insulating layers 40 and 50. The via-contact 52disposed in the pixel region PR1 may be in contact with the silicidelayer 35 a formed on the floating diffusion region 17. The via-contact52 disposed in the peripheral circuit region PR2 may be in contact withthe silicide layer 35 a formed on the third dopant region 19.Interconnections 54 may be disposed on the second interlayer insulatinglayer 50. The interconnections 54 may be in contact with thevia-contacts 52, respectively. The third interlayer insulating layer 60may be disposed on the second interlayer insulating layer 50 to coverthe interconnections 54.

A color filter 81 may be disposed on the third interlayer insulatinglayer 60 of the pixel region PR1. The color filter 81 may overlap withthe photoelectric conversion element PD. A planarization layer 83covering the color filter 81 may be disposed on the third interlayerinsulating layer 60. The planarization layer 83 may include a pluralityof refractive layers. A micro-lens 85 may be disposed on theplanarization layer 83. The micro-lens 84 may overlap with the colorfilter 81.

FIG. 4A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a second embodiment ofthe inventive concepts. FIG. 4B is an enlarged view of a portion ‘B’ ofFIG. 4A. In the present embodiment, the same elements as described inthe first embodiment will be indicated by the same reference numerals orthe same reference designators. The descriptions to the same elements asin the first embodiment will be omitted or mentioned briefly for thepurpose of ease and convenience in explanation.

Referring to FIG. 4A, a first dielectric layer 34 may be formed on thesemiconductor substrate 10 of the pixel region PR1. The first dielectriclayer 34 may conformally cover the top surface of the semiconductorsubstrate 10, and the top surface and the sidewall of the shutter gateSG, and the top surface and the sidewall of the transfer gate TG.Spacers 44 may be disposed on the sidewalls of the shutter gate SG withthe first dielectric layer 34 interposed therebetween. The spacer 44 mayinclude a second dielectric pattern 36 a and a third dielectric pattern37 a that are sequentially stacked on the first dielectric layer 34. Asecond dielectric layer 36 and a third dielectric layer 37 may besequentially stacked on the first dielectric layer 34 exposed by thelight shielding layer 45. The second dielectric layer 36 and the thirddielectric layer 37 may constitute a silicide blocking layer SBL. Adielectric layer 31 may include the first, second, and third dielectriclayers 34, 36, and 37. The second dielectric pattern 36 a may includethe same material as the second dielectric layer 36. The thirddielectric pattern 37 a may include the same material as the thirddielectric layer 37. The first dielectric layer 34 may include a siliconnitride (SiN) layer. The second dielectric layer 36 may include asilicon oxide (SiO₂) layer, and the third dielectric layer 37 mayinclude a silicon oxynitride (SiON) layer.

Referring to FIGS. 4A and 4B, the light shielding layer 45 may cover thefirst dielectric layer 34 and the second spacer 44 on the shutter gateSG. A first thickness Ta of the first dielectric layer 34 disposedbetween the top surface of the semiconductor substrate 10 and the bottomsurface of the first portion of the light shielding layer 45 may besmaller than a second thickness Tb of the dielectric layer 31 disposedon the top surface of the semiconductor substrate 10 not covered by thelight shielding layer 45. Some embodiments provide that the secondthickness Tb of the dielectric layer 31 corresponds to a sum ofthicknesses of the first, second, and third dielectric layers 34, 36,and 37.

The first thickness t1 of the first portion, covering the sidewalls ofthe shutter gate SG, of the light shielding layer 45 may be greater thanthe second thickness t2 of the second portion, disposed on the topsurface of the shutter gate SG, of the light shielding layer 45. Thefirst thickness t1 of the first portion of the light shielding layer 45corresponds to a vertical height from the top surface of the firstdielectric layer 34 disposed under the light shielding layer 45 to thetop surface of the first portion of the light shielding layer 45. Thesecond thickness t2 of the second portion of the light shielding layer45 corresponds to a vertical height from the top surface of the firstdielectric layer 34 formed on the top surface of the shutter gateelectrode 21 b to the top surface of the second portion of the lightshielding layer 45. The top surface of the first dielectric layer 34 maybe coplanar with the bottom surface of the light shielding layer 45.

Referring again to FIG. 4A, the third dielectric layer 37 may beconformally formed on the semiconductor substrate 10 of the peripheralcircuit region PR2. The third dielectric layer 37 may be formed on theprotection dielectric layer 22. The third dielectric layer 37 may coverthe top surface and the sidewall of the peripheral circuit gate PG.

The interlayer insulating structure 70 including the first to thirdinterlayer insulating layers 40, 50, and 60 may be disposed on thesemiconductor substrate 10. The via-contacts 52 may penetrate the secondand first interlayer insulating layers 50 and 40 so as to beelectrically connected to the silicide layers 35 a. The via-contacts 52may be electrically connected to the interconnections 54 disposed on thesecond interlayer insulating layer 50. The planarization layer 83, thecolor filter 81, and the micro-lens 85 may be disposed on the interlayerinsulating structure 70 of the pixel region PR1.

FIG. 5A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a third embodiment ofthe inventive concepts. FIG. 5B is an enlarged view of a portion ‘C’ ofFIG. 5A. In the present embodiment, the same elements as described inthe first and second embodiments will be indicated by the same referencenumerals or the same reference designators. The descriptions to the sameelements as in the first and second embodiments will be omitted ormentioned briefly for the purpose of ease and convenience inexplanation.

Referring to FIG. 5A, the first dielectric layer 34 may conformallycover the top surface of the semiconductor substrate 10, the top surfaceand the sidewall of the shutter gate SG and the top surface and thesidewall of the transfer gate TG. The second dielectric layer 36 may beconformally formed on the first dielectric layer 34. The thirddielectric pattern 37 a may be disposed on the sidewall of the shuttergate SG with the first and second dielectric layers 34 and 36 interposedtherebetween. The third dielectric layer 37 may be formed to cover thefloating diffusion region 17.

The light shielding layer 45 may cover the shutter gate SG and the thirddielectric pattern 37 a on the second dielectric layer 36. Each ofbottom surfaces, which are disposed at both sides of the shutter gateSG, respectively, of the first portion of the light shielding layer 45may include a first bottom surface 38 and a second bottom surface 42.Here, the first bottom surface 38 may be lower than the top surface ofthe first dielectric layer 34 and higher than the top surface of thesemiconductor substrate 10. The second bottom surface 42 may be disposedbetween the first bottom surface 38 and the third dielectric pattern 37a when viewed from a plan view. The second bottom surface 42 may behigher than the first bottom surface 38 and may be coplanar with the topsurface of the second dielectric layer 36.

Referring to FIGS. 5A and 5B, a first thickness t1 of the lightshielding layer 45 from the first bottom surface 38 to the top surfaceof the first portion of the light shielding layer 45 may be greater thanthe second thickness t2 of the second portion, covering the top surfaceof the shutter gate electrode 21 b, of the light shielding layer 45. Athird thickness t3 of the light shielding layer 45 from the secondbottom surface 42 to the top surface of the first portion of the lightshielding layer 45 may be smaller than the first thickness t1 andgreater than the second thickness t2.

A dielectric layer 31 according to some embodiments may consist of thefirst and second dielectric layers 34 and 36. A first thickness Ta ofthe first dielectric layer 34 between the top surface of thesemiconductor substrate 10 and the first bottom surface 38 may besmaller than a second thickness Tb of the dielectric layer 31 notcovered by the light shielding layer 45. The second thickness Tb of thedielectric layer 31 may be a sum of thicknesses of the first and seconddielectric layers 34 and 36. The dielectric layer 31 may have a thirdthickness Tc between the top surface of the semiconductor substrate 10and the second bottom surface 42. The third thickness Tc of thedielectric layer 31 may be equal to the second thickness Tb of thedielectric layer 31.

FIG. 6A is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 2 to illustrate an image sensor according to a fourth embodiment ofthe inventive concepts, and FIG. 6B is an enlarged view of a portion ‘D’of FIG. 6A. In the present embodiment, the same elements as described inthe first to third embodiments will be indicated by the same referencenumerals or the same reference designators. The descriptions to the sameelements as in the first to third embodiments will be omitted ormentioned briefly for the purpose of ease and convenience inexplanation.

Referring to FIG. 6A, a first dielectric layer 34 and a seconddielectric layer 36, which cover the shutter and transfer gates SG andTG may be sequentially formed on the semiconductor substrate 10 of thepixel region PR1. The first and second dielectric layers 34 and 36 mayexpose the floating diffusion region 17. A third dielectric layer 37 maybe disposed between the light shielding layer 45 and the seconddielectric layer 36. The third dielectric layer 37 may extend onto thetop surface of the second dielectric layer 36 covering the photoelectricconversion element PD. In addition, the third dielectric layer 37 mayfurther extend onto the protection dielectric layer 22 covering thefloating diffusion region 17.

The third dielectric layer 37 covering the shutter gate SG may bedisposed on the second dielectric layer 36. The first bottom surface 38,which is disposed at a first side of the shutter gate SG, of the firstportion of the light shielding layer 45 may be lower than the topsurface of the first dielectric layer 34 and higher than the top surfaceof the semiconductor substrate 10. A second bottom surface 42, which isdisposed at the first side of the shutter gate SG, of the first portionof the light shielding layer 45 may be coplanar with the top surface ofthe third dielectric layer 37. A third bottom surface 46, which isdisposed at a second side of the shutter gate SG, of the first portionof the light shielding layer 45 may be coplanar with the top surface ofthe third dielectric layer 37.

Referring to FIGS. 6A and 6B, the first thickness t1 of the lightshielding layer 45 from the first bottom surface 38 to the top surfaceof the first portion may be greater than the second thickness t2 of thesecond portion of the light shielding layer 45. A third thickness t3 ofthe light shielding layer 45 from the second bottom surface 42 to thetop surface of the second portion may be smaller than the firstthickness t1 and greater than the second thickness t2. A fourththickness t4 of the light shielding layer 45 from the third bottomsurface 46 to the top surface of the first portion of the lightshielding layer 45 may be smaller than the first thickness t1 andgreater than the second thickness t2. The fourth thickness t4 may beequal to the third thickness t3.

A first thickness Ta of the first dielectric layer 34 between the topsurface of the semiconductor substrate 10 and the first bottom surface38 of the light shielding layer 45 may be smaller than a secondthickness Tb of the dielectric layer 31 that is covered by the lightshielding layer 45 and is adjacent the transfer gate TG. The secondthickness Tb of the dielectric layer 31 may be smaller than a thirdthickness Tc of the dielectric layer 31 between the top surface of thesemiconductor substrate 10 and the second bottom surface 42 of the lightshielding layer 45. A fourth thickness of the dielectric layer 31between the top surface of the semiconductor substrate 10 and the thirdbottom surface 46 of the light shielding layer 45 may be equal to thethird thickness Tc of the dielectric layer 31. The second thickness Tbof the dielectric layer 31 may be a sum of thicknesses of the first andsecond dielectric layers 34 and 36. Each of the third and fourththicknesses Tc and Td may be a sum of thicknesses of the first to thirddielectric layers 34, 36, and 37.

FIG. 7 is a plan view illustrating an image sensor according to a fifthembodiment of the inventive concepts. FIG. 8 is a cross-sectional viewtaken along lines III-III′ and VI-VI′ of FIG. 7 to illustrate the imagesensor according to the fifth embodiment of the inventive concepts. Inthe present embodiment, the same elements as described in the firstembodiment will be indicated by the same reference numerals or the samereference designators. The descriptions to the same elements as in thefirst embodiment will be omitted or mentioned briefly for the purpose ofease and convenience in explanation.

Referring to FIGS. 7 and 8, a light shielding layer 45 may be formed tocover both the shutter gate SG and the transfer gate TG. In more detail,the light shielding layer 45 may cover the top surface and the sidewallsof the shutter gate SG and a top surface and at least one sidewall ofthe transfer gate TG. In some embodiments, the light shielding layer 45may cover one sidewall of the transfer gate TG which is adjacent theshutter gate SG. A space between the shutter gate SG and the transfergate TG may be completely filled with the light shielding layer 45. Thedielectric layer 31 being in contact with the light shielding layer 45may be thinner than the dielectric layer 31 that is exposed by the lightshielding layer 45 and is in contact with a bottom surface of the firstinterlayer insulating layer 40.

FIGS. 9A to 9I are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate a method of fabricating the image sensoraccording to the first embodiment of the inventive concepts.

Referring to FIG. 9A, a semiconductor substrate 10 may include a pixelregion PR1 and a peripheral circuit region PR2. The semiconductorsubstrate 10 may be doped with P-type dopants. A device isolation layer13 may be formed in the semiconductor substrate 10 to define a firstactive region 11 and a second active region 12 in the pixel region PR1and the peripheral circuit region PR2, respectively. A trench (notshown) may be formed in the semiconductor substrate 10, and the deviceisolation layer 13 may be formed by filling the trench with aninsulating material (e.g., an insulating oxide). A charge storage region14 and a well region 16 may be formed in the semiconductor substrate 10(e.g., the first active region 11). In more detail, P-type dopants maybe injected deep into the semiconductor substrate 10 to form the wellregion 16, and N-type dopants may be injected shallow into thesemiconductor substrate 10 to form the charge storage region 14 over thewell region 16. A separation region 18 may be formed in thesemiconductor substrate 10 (e.g., the first active region 11). Theseparation region 18 may be spaced apart from the charge storage region14 and may be formed at a side of the charge storage region 14. Theseparation region 18 may be formed by injecting P-type dopants into thesemiconductor substrate 10.

A shutter gate SG, a transfer gate TG, and a peripheral circuit gate PGmay be formed on the semiconductor substrate 10. The shutter gate SG andthe transfer gate TG may be formed on the first active region 11 of thepixel region PR1, and the peripheral circuit gate PG may be formed onthe second active region 12 of the peripheral circuit region PR2. Theshutter gate SG may be formed on the separation region 18 and the chargestorage region 14. The transfer gate TG may be formed on thesemiconductor substrate 10 at another side of the charge storage region14. In some embodiments, an insulating layer and a gate electrode layermay be sequentially formed on the semiconductor substrate 10, and theinsulating layer and the gate dielectric layer may be patterned to formthe shutter gate SG, the transfer gate TG, and the peripheral circuitgate PG. The shutter gate SG may include a shutter gate insulating layer21 a and a shutter gate electrode 21 b, and the transfer gate TG mayinclude a transfer gate insulating layer 23 a and a transfer gateelectrode 23 b. The peripheral circuit gate PG may include a peripheralcircuit gate insulating layer 25 a and a peripheral circuit gateelectrode 25 b.

An ion implantation mask pattern (not shown) may be formed to cover theshutter gate SG and the transfer gate PG, and N-type dopants may beimplanted, using the ion implantation mask pattern and the peripheralcircuit gate PG as ion implantation masks, into the semiconductorsubstrate 10. Thus, a first dopant region 15 a may be formed in thesemiconductor substrate 10 (e.g., the first active region 11) betweenthe device isolation layer 13 and the separation region 18. The firstdopant region 15 a may be adjacent the shutter gate SG. In addition, afloating diffusion region 17 adjacent the transfer gate TG may be formedin the semiconductor substrate 10 (e.g., the first active region 11).The floating diffusion region 17 may be spaced apart from the chargestorage region 14. Furthermore, third dopant regions 19 may be formed inthe semiconductor substrate 10 (e.g., the second active region 12) atboth sides of the peripheral circuit gate PG. The third dopant regions19 may be source/drain regions or well regions.

After the formation of the first dopant region 15 a, a P-type dopant maybe injected into the first dopant region 15 a to form a second dopantregion 15 b that is shallower than the first dopant region 15 a. Thefirst dopant region 15 a and the second dopant region 15 b mayconstitute a photoelectric conversion element PD.

Referring to FIG. 9B, a dielectric layer 31 may be formed on thesemiconductor substrate 10. The dielectric layer 31 may be formed toconformally cover the top surface of the semiconductor substrate 10 andsurfaces of the gates SG, TG, and PG. The dielectric layer 31 mayinclude a silicon nitride layer.

Referring to FIG. 9C, a first mask pattern 33 may be formed on thedielectric layer 31. The first mask pattern 33 may cover the shuttergate SG and the transfer gate TG. At this time, the first mask pattern33 may expose the dielectric layer 31 that is disposed on a portion ofthe floating diffusion region 17 and the semiconductor substrate 10 ofthe peripheral circuit region PR2. The dielectric layer 31 exposed bythe first mask pattern 33 may be removed to expose the semiconductorsubstrate 10 and the peripheral circuit gate PG. A first metal layer 35may be formed on the semiconductor substrate 10. The first metal layer35 may be formed on the exposed top surface of the semiconductorsubstrate 10 and the peripheral circuit gate PG. The first metal layer35 may cover the exposed portion of the floating diffusion region 17,the top surface of the semiconductor substrate 10 of the peripheralcircuit region PR2, and the surface of the peripheral circuit gate PG.In some embodiments, even though not shown in FIG. 9C, the first metallayer 35 may also be formed on the first mask pattern 33. The firstmetal layer 35 may include cobalt (Co), titanium (Ti), nickel (Ni),and/or tungsten (W).

Referring to FIG. 9D, a thermal treatment (e.g., a rapid thermal process(RTP)) may be performed on the semiconductor substrate 10 having thefirst metal layer 35 to form silicide layers 35 a. The first metal layer35 may react with silicon included in the semiconductor substrate 10and/or the peripheral circuit gate electrode 25 b to form the silicidelayers 35 a. Thus, the silicide layers 35 a may be formed on the portionof the floating diffusion region 17, the third dopant regions 19, andthe surface of the peripheral circuit gate electrode 25 b, respectively.In some embodiments, even though not shown in the drawings, gate spacers(not shown) may be formed on sidewalls of the gates SG, TG, and PGbefore the formation of the dielectric layer 31. In this case, the firstmetal layer 35 may be in contact with the top surface of the peripheralcircuit gate electrode 25 b. Thus, the silicide layer 35 a on thesurface of the peripheral circuit gate electrode 21 b may be confinedlyformed on the top surface of the peripheral circuit gate electrode 21 b.An unreacted portion of the first metal layer 35 may be removed afterthe formation of the silicide layers 35 a.

A protection dielectric layer 22 may be formed on the semiconductorsubstrate 10 exposed by the first mask pattern 33. The protectiondielectric layer 22 may cover the silicide layers 35 a. A thickness ofthe protection dielectric layer 22 may be substantially equal to that ofthe dielectric layer 31. However, the inventive concepts are not limitedthereto. For example, the protection dielectric layer 22 may include asilicon nitride layer.

Referring to FIG. 9E, the first mask pattern 33 may be removed, and afirst interlayer insulating layer 40 may be then formed on thesemiconductor substrate 10. The first interlayer insulating layer 40 maybe patterned to form an opening 41 overlapping with the shutter gate SG.In some embodiments, a photoresist pattern (not shown) may be formed onthe first interlayer insulating layer 40, and the first interlayerinsulating layer 40 may be etched using the photoresist pattern as anetch mask to form the opening 41. The opening 41 may expose a portion ofthe dielectric layer 31 that covers a top surface and sidewalls of theshutter gate SG and extends from the sidewalls of the shutter gate SGonto a portion of the top surface of the semiconductor substrate 10.

In some embodiments, the opening 41 in the first interlayer insulatinglayer 40 may overlap with the shutter gate SG and the transfer gate TG.The opening 41 may expose a portion of the dielectric layer 31 thatcovers the shutter and transfer gates SG and TG and the semiconductorsubstrate 10 disposed between the shutter and transfer gates SG and TG.In this case, the light shielding layer 45 illustrated in FIG. 8 may beformed in a subsequent process.

Referring to FIG. 9F, an etch-back process may be performed on thesemiconductor substrate 10 having the first interlayer insulating layer40 with the opening 41. Thus, the dielectric layer 31 exposed by theopening 41 may be recessed.

Referring to FIGS. 9G and 9H, a second metal layer 43 may be formed onthe first interlayer insulating layer 40 to fill the opening 41. Thesecond metal layer 43 may include aluminum (Al) and/or tungsten (W).

The second metal layer 43 may be planarized unit a top surface of thefirst interlayer insulating layer 40 is exposed. Thus, the second metallayer 43 disposed on the top surface of the first interlayer insulatinglayer 40 may be removed, and a light shielding layer 45 may be formed tofill the opening 41. The light shielding layer 45 may be formed tocompletely cover the top surface and the sidewalls of the shutter gateSG. The planarization process may be performed using a chemicalmechanical polishing (CMP) process or an etch-back process. Due to theplanarization process, an entire top surface of the light shieldinglayer 45 may be substantially flat. In addition, the top surface of thelight shielding layer 45 may be substantially coplanar with the topsurface of the first interlayer insulating layer 40.

Referring to FIG. 9I, a second interlayer insulating layer 50 may beformed on the first interlayer insulating layer 40. Via-contacts 52 maybe formed to penetrate the second interlayer insulating layer 50, thefirst interlayer insulating layer 40, and the protection dielectriclayer 22. The via-contact 52 formed in the pixel region PR1 may beconnected to the silicide layer 35 a formed on the floating diffusionregion 17, and the via-contact formed in the peripheral circuit regionPR2 may be connected to the silicide layer 35 a formed on the thirddopant region 19. The via-contacts 52 may include a metal material suchas copper (Cu), aluminum (Al), or tungsten (W).

Referring again to FIG. 3A, interconnections 54 may be formed on thesecond interlayer insulating layer 50. The interconnections 54 may be incontact with the via-contacts 52. A third interlayer insulating layer 60may be formed on the second interlayer insulating layer 50 to cover theinterconnection 54. A color filter 81 may be formed on the thirdinterlayer insulating layer 60 in the pixel region PR1. The color filter81 may overlap with the photoelectric conversion element PD. In someembodiments, a color filter layer (not shown) may be formed on the thirdinterlayer insulating layer 60, and the color filter layer may bepatterned to form the color filter 81. Next, a planarization layer 83covering the color filter 81 may be formed on the third interlayerinsulating layer 60. The planarization layer 83 may include a pluralityof refractive layers. A micro-lens 85 overlapping with the color filter81 may be formed on the planarization layer 83.

FIGS. 10A to 10G are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate methods of fabricating the image sensoraccording to the second embodiment of the inventive concepts. In thepresent embodiment, the same elements as described in the firstembodiment will be indicated by the same reference numerals or the samereference designators. The descriptions to the same elements as in thefirst embodiment will be omitted or mentioned briefly for the purpose ofease and convenience in explanation.

Referring to FIG. 10A, a first dielectric layer 34 and a seconddielectric layer 36 may be sequentially and conformally formed on thesemiconductor substrate 10 having the shutter gate SG, the transfer gateTG, and the peripheral gate PG. The first dielectric layer 34 may be asilicon nitride (SiN) layer, and the second dielectric layer 36 may be asilicon oxide (SiO₂) layer. The first dielectric layer 34 and the seconddielectric layer 36 may constitute a silicide blocking layer SBL.

A first mask pattern 33 may be formed on the silicide blocking layer SBLof the pixel region PR1. The first mask pattern 33 may expose a portionof the silicide blocking layer SBL covering the floating diffusionregion 17 and the silicide blocking layer SBL disposed in the peripheralcircuit region PR2.

Referring to FIG. 10B, the silicide blocking layer SBL exposed by thefirst mask pattern 33 may be removed to expose the floating diffusionregion 17, the third dopant regions 19, and the peripheral circuit gateelectrode 25 b. The silicide layers 35 a may be formed on the exposedfloating diffusion region 17, the exposed third dopant regions 19, andthe exposed peripheral circuit gate electrode 25 b, respectively. Thesilicide layer 35 a may not be formed on the top surface of thesemiconductor substrate 10 that is covered by the silicide blockinglayer SBL. The protection dielectric layer 22 may be formed on thesemiconductor substrate 10 exposed by the first mask pattern 33. Thefirst mask pattern 33 may be removed after the formation of the silicidelayers 35 a.

Referring to FIG. 10C, a third dielectric layer 37 may be conformallyformed on the semiconductor substrate 10 of the pixel region PR1 and theperipheral circuit region PR2. In more detail, the third dielectriclayer 37 may cover a top surface of the second dielectric layer 36 and atop surface of the protection dielectric layer 22. The third dielectriclayer 37 may cover the protection dielectric layer 22 formed in theperipheral circuit region PR2. In addition, the third dielectric layer37 may also cover the protection dielectric layer 22 formed on thefloating diffusion region 17. The third dielectric layer 37 may be asilicon oxynitride (SiON) layer.

Referring to FIG. 10D, the first interlayer insulating layer 40 havingthe opening 41 may be formed on the semiconductor substrate 10. Thefirst interlayer insulating layer 40 may be formed to cover thephotoelectric conversion element PD, the transfer gate TG, and theperipheral circuit gate PD. The opening 41 may overlap with the shuttergate SG. In more detail, the opening 41 may expose a portion of thethird dielectric layer 37 that covers the top surface and the sidewallsof the shutter gate SG and extends onto the top surface of thesemiconductor substrate 10.

Referring to FIG. 10E, an etch-back process may be performed on thesemiconductor substrate 10 having the interlayer insulating layer 40.The third and second dielectric layers 37 and 36 under the opening 41may be etched by the etch-back process until the top surface of thefirst insulating layer 34 is exposed. As a result of the etch-backprocess, spacers 44 may be formed on the sidewalls of the shutter gateelectrode SG with the first dielectric layer 34 interposed therebetween.The spacer 44 may include a second dielectric pattern 36 a and a thirddielectric pattern 37 a. The second and third dielectric patterns 36 aand 37 a may correspond to portions of the second and third dielectriclayers 36 and 37 that remain under the opening 41 after the etch-backprocess.

Referring to FIGS. 10F and 10G, the light shielding layer 45 may beformed to fill the opening 41. The second interlayer insulating layer 50may be formed on the first interlayer insulating layer 40. Thevia-contacts 52 may be formed to penetrate the second and firstinterlayer insulating layers 50 and 40. The third dielectric layer 37may function as an etch stop layer when the second and first interlayerinsulating layers 50 and 40 are sequentially etched for the formation ofthe via-contacts 52. In more detail, the second and first interlayerinsulating layers 50 and 40 may be first etched using the thirddielectric layer 37 as the etch stop layer. Thereafter, the thirdinsulating layer 37 and the protection dielectric layer 22 may besecondly etched until the semiconductor substrate 10 is exposed. Thethird dielectric layer 37 used as the etch stop layer may prevent thetop surface of the semiconductor substrate 10 from being recessed.

Referring again to FIG. 4A, the interconnections 54 covering thevia-contacts 52 may be formed on the second interlayer insulating layer50. The third interlayer insulating layer 60 covering theinterconnections 54 may be formed on the second interlayer insulatinglayer 50. The color filter 81, the planarization layer 83, and themicro-lens 85 may be sequentially formed on the third interlayerinsulating layer 60 of the pixel region PR1.

FIGS. 11A to 11F are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate methods of fabricating the image sensoraccording to the third embodiment of the inventive concepts. In thepresent embodiment, the same elements as described in the first andsecond embodiments will be indicated by the same reference numerals orthe same reference designators. The descriptions to the same elements asin the first and second embodiments will be omitted or mentioned brieflyfor the purpose of ease and convenience in explanation.

Referring to FIG. 11A, a second mask pattern 39 may be formed on thesemiconductor substrate 10. In some embodiments, the second mask pattern39 may be formed on the third dielectric layer 37 of the structureillustrated in FIG. 10C. In detail, the second mask pattern 39 may coverthe shutter gate SG. In addition, the second mask pattern 39 may furthercover the floating diffusion region 17. Furthermore, the second maskpattern 39 may completely cover the semiconductor substrate 10 of theperipheral circuit region PR2.

Referring to FIG. 11B, the third dielectric layer 37 exposed by thesecond mask pattern 39 may be etched to form a third dielectric pattern37 a covering the shutter gate SG. Thus, the second dielectric layer 36formed on the photoelectric conversion element PD and the transfer gateTG may be exposed.

Referring to FIG. 11C, the second mask pattern 39 may be removed afterthe formation of the third dielectric pattern 37 a. The first interlayerinsulating layer 40 may be formed on the semiconductor substrate 10. Thefirst interlayer insulating layer 40 may be formed to cover thephotoelectric conversion element PD, the transfer gate TG, the floatingdiffusion region 17, and the semiconductor substrate 10 of theperipheral circuit region PR2. The first interlayer insulating layer 40may include the opening 41 overlapping the shutter gate SG. In moredetail, the opening 41 may expose the third dielectric pattern 37 acovering the shutter gate SG and a portion of the second dielectriclayer 36. The portion of the second dielectric layer 36, which isexposed by the opening 41, may be adjacent both ends of the thirddielectric pattern 37 a and be exposed by the third dielectric pattern37 a.

Referring to FIG. 11D, an etch-back process may be performed on thefirst interlayer insulating layer 40 having the opening 41 to etch thethird dielectric pattern 37 a. At this time, the portion of the seconddielectric layer 36 exposed by the opening 41 and the third dielectricpattern 37 a may be etched by the etch-back process, and the firstdielectric layer 34 disposed under the portion of the second dielectriclayer 36 may be recessed by over-etching. After the etch-back process,the third dielectric pattern 37 a having a spacer shape may remain onthe sidewalls of the shutter gate SG with the second dielectric layer 36interposed therebetween.

Referring to FIG. 11E, the light shielding layer 45 may be formed tofill the opening 41. Thus, first bottom surfaces 38 of the lightshielding layer 45 at both sides of the shutter gate SG may be lowerthan the top surface of the first dielectric layer 34 and higher thanthe top surface of the semiconductor substrate 10. A second bottomsurface 42 of the light shielding layer 45 disposed between the thirddielectric pattern 37 a and each of the first bottom surfaces 38 may becoplanar with the top surface of the second dielectric layer 36.

Referring to FIG. 11F, the second interlayer insulating layer 50 may beformed on the first interlayer insulating layer 40. The via-contacts 52may be formed to penetrate the second and first interlayer insulatinglayers 50 and 40, the third dielectric layer 37, and the protectionlayer 22.

Referring again to FIG. 5A, the interconnections 54 covering thevia-contacts 52 may be formed on the second interlayer insulating layer50. The third interlayer insulating layer 60 covering theinterconnections 54 may be formed on the second interlayer insulatinglayer 50. The color filter 81, the planarization layer 83, and themicro-lens 85 may be sequentially formed on the third interlayerinsulating layer 60 of the pixel region PR1.

FIGS. 12A to 12E are cross-sectional views taken along lines I-I′ andII-II′ of FIG. 2 to illustrate methods of fabricating the image sensoraccording to the fourth embodiment of the inventive concepts. In thepresent embodiment, the same elements as described in the first tofourth embodiments will be indicated by the same reference numerals orthe same reference designators. The descriptions to the same elements asin the first to fourth embodiments will be omitted or mentioned brieflyfor the purpose of ease and convenience in explanation.

Referring to FIG. 12A, a second mask pattern 39 may be formed on thesemiconductor substrate 10. The second mask pattern 39 may be formed onthe third dielectric layer 37 except a portion of the third dielectriclayer 37 that is formed on the transfer gate TG. The third dielectriclayer 37 exposed by the second mask pattern 39 may be removed to exposethe second dielectric layer 36 formed on the transfer gate TG.

Referring to FIG. 12B, the second mask pattern 39 may be removed, andthen, the first interlayer insulating layer 40 may be formed on thesemiconductor substrate 10. The first interlayer insulating layer 40 maybe formed on the photoelectric conversion element PD, the transfer gateTG, the floating diffusion region 17, and the semiconductor substrate 10of the peripheral circuit region PR2. The first interlayer insulatinglayer 40 may have the opening 41 overlapping with the shutter gate SG.In more detail, the opening 41 may expose the third dielectric layer 37covering the shutter gate SG. In addition, the opening 41 may alsoexpose the third dielectric layer 37 that extends from one sidewall ofthe shutter gate SG onto the photoelectric conversion element PD.Furthermore, the opening 41 may further expose a portion of the seconddielectric layer 36 that is exposed by the third dielectric layer 37disposed between the shutter gate SG and the transfer gate TG.

Referring to FIG. 12C, an etch-back process may be performed on thefirst interlayer insulating layer 40 having the opening 41 to etch theportion of the second dielectric layer 36 exposed by the thirddielectric layer 37. During the etch-back process, the second dielectriclayer 36 may be over-etched to recess the top surface of the firstdielectric layer 34 disposed thereunder.

Referring to FIG. 12D, the light shielding layer 45 may be formed tofill the opening 41. Thus, a first bottom surface 38 of the lightshielding layer 45 at a side of the shutter gate SG may be lower thanthe top surface of the first dielectric layer 34 and higher than the topsurface of the semiconductor substrate 10. A second bottom surface 42 ofthe light shielding layer 45 disposed at the side of the shutter gate SGmay be coplanar with the top surface of the third dielectric layer 37. Athird bottom surface 46 of the light shielding layer 45 disposed atanother side of the shutter gate SG may be coplanar with the secondbottom surface 42 of the light shielding layer 45.

Referring to FIG. 12E, the second interlayer insulating layer 50 may beformed on the first interlayer insulating layer 40. The via-contacts 52may be formed to penetrate the second and first interlayer insulatinglayers 50 and 40, the third dielectric layer 37, and the protectionlayer 22.

Referring again to FIG. 6A, the interconnections 54 covering thevia-contacts 52 may be formed on the second interlayer insulating layer50. The third interlayer insulating layer 60 covering theinterconnections 54 may be formed on the second interlayer insulatinglayer 50. The color filter 81, the planarization layer 83, and themicro-lens 85 may be sequentially formed on the third interlayerinsulating layer 60 of the pixel region PR1.

FIGS. 13 to 17 illustrate examples of multimedia devices implementedwith image sensors according to some embodiments of the inventiveconcepts.

The image sensor according to some embodiments of the inventive conceptsmay be applied to various multimedia devices having an imagephotographing function. For example, the image sensor of someembodiments of the inventive concepts may be applied to a mobile and/orsmart phone 1000 illustrated in FIG. 13 and/or a tablet and/or smarttablet 2000 illustrated in FIG. 14. In addition, the image sensoraccording to the aforementioned embodiments may be applied to a notebookcomputer 3000 illustrated in FIG, 15 and/or a television or smarttelevision 4000 illustrated in FIG. 16. Furthermore, the image sensoraccording to the aforementioned embodiments may be applied to a digitalcamera or camcorder 5000 illustrated in FIG. 17.

FIG. 18 is a schematic block diagram illustrating an image processingsystem including an image sensor according to some embodiments of theinventive concepts.

The electronic device may be a digital camera and/or a mobile device.Referring to FIG. 18, a digital camera system may include an imagesensor 6000, a processor 6100, a memory device 6200, a display device6300, and a system bus 6400. The image sensor 6000 may capture externalimage information in response to control signals of the processor 6100.The image sensor 6000 may include at least one of the image sensors ofthe aforementioned embodiments of the inventive concepts. The processor6100 may store the captured image information in the memory device 6200through the system bus 6400. The process 6100 may display the imageinformation stored in the memory device 6200 on the display device 6300.

According to some embodiments of the inventive concepts, the imagesensor includes the light shielding layer that shields the lightprovided toward the charge storage region. The first thickness of thefirst portion, covering the sidewalls of the shutter gate, of the lightshielding layer is greater than the second thickness of the secondportion, covering the top surface of the shutter gate, of the lightshielding layer. Thus, it is possible to effectively prevent the lightwhich is provided toward the charge storage region along the sidewallsof the shutter gate.

While the inventive concepts have been described with reference toexample embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirits and scopes of the inventive concepts. Therefore, itshould be understood that the above embodiments are not limiting, butillustrative. Thus, the scopes of the inventive concepts are to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing description.

What is claimed is:
 1. An image sensor comprising: a substrate; aphotoelectric conversion element that is disposed in the substrate; afirst storage region that is disposed in the substrate and that isspaced apart from the photoelectric conversion element; a gate that ison the first storage region; a light shielding layer that covers thegate; a dielectric layer that is between the gate and the lightshielding layer and that extends onto a top surface of the substrate; aninterlayer insulating structure on the light shielding layer on thesubstrate; and a micro-lens that is on the interlayer insulatingstructure and that overlaps with the photoelectric conversion element,wherein the light shielding layer comprises: a first portion that is ona sidewall of the gate; and a second portion that is on a top surface ofthe gate, wherein the first portion of the light shielding layer has afirst thickness corresponding to a vertical height from a bottom surfaceof the first portion to a top surface of the first portion, and whereinthe first thickness of the first portion of the light shielding layer isgreater than a second thickness of the second portion of the lightshielding layer.
 2. The image sensor of claim 1, wherein the top surfaceof the first portion of the light shielding layer is coplanar with a topsurface of the second portion of the light shielding layer.
 3. The imagesensor of claim 1, wherein a first thickness of the dielectric layerbetween the top surface of the substrate and a top surface of thedielectric layer that is covered with the light shielding layer issmaller than a second thickness of the dielectric layer between the topsurface of the substrate and a top surface of the dielectric layer thatis not covered by the light shielding layer.
 4. The image sensor ofclaim 1, wherein the dielectric layer comprises a first dielectric layerand a second dielectric layer, wherein the first dielectric layer coversa surface of the gate and extends onto the top surface of the substrate,and wherein the second dielectric layer is stacked on the firstdielectric layer that is not covered by the light shielding layer. 5.The image sensor of claim 4, wherein the first portion of the lightshielding layer has a bottom surface coplanar with a top surface of thefirst dielectric layer.
 6. The image sensor of claim 4, wherein thesecond dielectric layer is further disposed between the first dielectriclayer and the light shielding layer.
 7. The image sensor of claim 6,wherein at least a portion of a bottom surface of the first portion ofthe light shielding layer is in contact with a first top surface of thefirst dielectric layer, and wherein the first top surface of the firstdielectric layer is recessed relative to a second top surface of thefirst dielectric layer that is not covered by the light shielding layer.8. The image sensor of claim 7, wherein the first portion of the lightshielding layer comprises: a first bottom surface; and a second bottomsurface that is between the first bottom surface and the gate, whereinthe first bottom surface is coplanar with the first top surface of thefirst dielectric layer, and wherein the second bottom surface iscoplanar with a top surface of the second dielectric layer.
 9. The imagesensor of claim 7, wherein the dielectric layer further comprises: athird dielectric layer that is stacked on the second dielectric layer.10. The image sensor of claim 9, wherein the first portion of the lightshielding layer that is at a side of the gate comprises: a first bottomsurface that is coplanar with the first top surface of the firstdielectric layer; and a second bottom surface that is disposed betweenthe gate and the first bottom surface, wherein the second bottom surfaceis coplanar with a top surface of the third dielectric layer, andwherein the first portion of the light shielding layer that is atanother side of the gate comprises: a third bottom surface that iscoplanar with the top surface of the third dielectric layer.
 11. Theimage sensor of claim 4, wherein the first dielectric layer includes asilicon nitride layer.
 12. The image sensor of claim 4, wherein thesecond dielectric layer includes a silicon oxide layer.
 13. The imagesensor of claim 1, further comprising: a separation region in thesubstrate between the photoelectric conversion element and a side of thefirst storage region; a well region in the substrate under the firststorage region; and a second storage region in the substrate and spacedapart from another side of the first storage region.
 14. The imagesensor of claim 13, wherein the gate comprises a shutter gate, the imagesensor further comprising: a transfer gate that is on the substratebetween the first storage region and the second storage region.
 15. Theimage sensor of claim 14, wherein the light shielding layer extends ontoa top surface of the transfer gate.
 16. An image sensor comprising: asubstrate including a pixel region and a peripheral circuit region; aphotoelectric conversion element that is in the pixel region of thesubstrate; a storage region that is disposed in the pixel region of thesubstrate and that is spaced apart from the photoelectric conversionelement; a shutter gate that is on the storage region in the pixelregion; a peripheral circuit gate that is in the peripheral circuitregion; a light shielding layer that includes a first portion thatcovers a sidewall of the shutter gate and a second portion that covers atop surface of the shutter gate; a dielectric layer that is between theshutter gate and the light shielding layer and that is on the peripheralcircuit gate; an interlayer insulating structure that covers the lightshielding layer on the substrate and a portion of the dielectric layerthat is in the peripheral circuit region; a micro-lens that is on theinterlayer insulating structure and that overlaps with the photoelectricconversion element; and a color filter that is in the interlayerinsulating structure and that is between the micro-lens and thephoto-electric conversion element, wherein the first portion of thelight shielding layer has a first thickness corresponding to a verticalheight from a bottom surface of the first portion to a top surface ofthe first portion, and wherein the first thickness of the first portionof the light shielding layer is greater than a second thickness of thesecond portion of the light shielding layer.
 17. The image sensor ofclaim 16, wherein the storage region comprises a first storage region,the sensor further comprising: a separation region in the substratebetween the photoelectric conversion element and a side of the firststorage region; a well region in the substrate under the first storageregion; a second storage region in the substrate and spaced apart fromanother side of the first storage region; and a transfer gate that is onthe substrate between the first storage region and the second storageregion.
 18. The image sensor of claim 17, wherein the light shieldinglayer extends onto a top surface of the transfer gate, wherein a firstthickness of the dielectric layer between the top surface of thesubstrate and a top surface of the dielectric layer that is covered withthe light shielding layer is smaller than a second thickness of thedielectric layer between the top surface of the substrate and a topsurface of the dielectric layer that is not covered by the lightshielding layer, wherein the dielectric layer comprises a firstdielectric layer and a second dielectric layer, wherein the firstdielectric layer covers a surface of the shutter gate and extends ontothe top surface of the substrate, and wherein the second dielectriclayer is stacked on the first dielectric layer that is not covered bythe light shielding layer.
 19. The image sensor of claim 18, wherein thesecond dielectric layer is further disposed between the first dielectriclayer and the light shielding layer, wherein at least a portion of abottom surface of the first portion of the light shielding layer is incontact with a first top surface of the first dielectric layer, andwherein the first top surface of the first dielectric layer is recessedrelative to a second top surface of the first dielectric layer that isnot covered by the light shielding layer.
 20. The image sensor of claim19, wherein the first portion of the light shielding layer comprises: afirst bottom surface; and a second bottom surface that is between thefirst bottom surface and the shutter gate, wherein the first bottomsurface is coplanar with the first top surface of the first dielectriclayer, and wherein the second bottom surface is coplanar with a topsurface of the second dielectric layer.